Three Years Later

Three years after the April 20, 2010 Deepwater Horizon blowout that killed 11 people and released nearly five million barrels of oil into the Gulf of Mexico many questions remain about the long term impact of the largest ever accidental release of oil into the marine environment.

It was not just the sheer volume of oil that leaked from the well that made dealing with this unprecedented disaster's aftermath unique. The point where the oil was escaping was almost a mile beneath the Gulf's surface, creating problems with which responders had never before been confronted. And, the decision to use more than 1.8 million gallons of dispersants meant oil that would normally rise to the surface would remain suspended beneath the surface in globules making it difficult to reach and impossible to determine how much was missed during clean-up operations.

“There has never been anything like this blowout and we were just not prepared in any sense of the word to deal with it,” said Dr. Larry McKinney, Director of the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University-Corpus Christi.” The nature of the leak and the use of dispersants at depth essentially turned the spill upside down.”

During all previous spills the oil rose to the surface and drifted with the wind so modern oil spill response equipment and techniques have been designed to deal with that scenario. However, in the case of Deepwater Horizon, plumes of oil drifted with currents at various depths, settled to the bottom or dispersed throughout the water column making the use of skimmer ships, floating booms and controlled burns less effective. The use of dispersants at depth was employed for two primary reasons – keeping as much oil out of highly productive coastal waters and wetlands and facilitating microbial breakdown of the oil.

The Coastal and Marine Geospatial Lab, led by Dr. Jim Gibeaut, HRI Endowed Chair of Geospatial Sciences, is mapping shorelines and modeling rates of shoreline change in areas impacted by the Deepwater Horizon oil spill. This work is being conducted on behalf of the Trustees of the Natural Resource Damage Assessment (NRDA).

“The Gulf of Mexico hosts a diverse and abundant microbial community that targets oil as an energy source,” said Dr. McKinney. “The Natural Resources Commission (NRC) estimates that around 1.2 million barrels of oil leaked from natural seeps all around the Gulf during the 1990s, enough to fill a super tanker. And while, over time, microbes have evolved, the question about the wisdom of dispersing oil at depth versus letting it rise to the surface where our technology and procedures can deal with it remains to be answered.”

Dr. Wes Tunnell, HRI Associate Director and Endowed Chair of Biodiversity and Marine Conservation, studied the Ixtoc I oil spill from the southern Gulf of Mexico in 1979 and 1980 when it impacted Texas beaches and Mexican coral reefs and beaches. In Texas, life in the sand of South Texas beaches recovered in only a few years. But after tracking an Ixtoc tar mat in the lagoon of Enmedio Reef off Veracruz for about 15 years (1980-1993), he went back in the summer of 2010 and still found remnants of the mat.

It is unfortunate that little research was conducted after the Ixtoc spill, because we could have used that knowledge to help us with the Deepwater spill,” said Dr. Tunnell. “On the other hand, I am very happy that so much research is going on now, as we will learn immeasurably from this spill and that could help us make better decisions regarding future spills."
To date, studies on the use of dispersants have not yet shed much light on this issue. Research funded by the Gulf of Mexico Research Initiative (GOMRI) are still underway and NRDA documents are not generally available for review as the court case to resolve damage claims has not yet been settled. Some environmental scientists have expressed that dispersants may have added to the dangers from the spill because currents picked them up and distributed them throughout the Gulf.

Dr. Paul Montagna, HRI Endowed Chair of Ecosystems and Modeling, is the technical lead for the nation’s assessment of the effects of the Deepwater Horizon blowout on deep-sea benthos communities. His work will be the basis for perhaps millions of dollars in restoration funding to address these impacts. 

“I think it is premature to invest heavily in dispersant strategies until all the evidence is in,” said Dr. McKinney.” It may very well turn out that the use of dispersants to make the oil more available to microbial degradation is the best strategy. But we need to understand just what this may be doing to the deep Gulf where many animals like corals measure life spans in the hundreds of years and processes are much slower and less dynamic than in coastal waters.”